Dr. Craig Wright, cryptocurrency pioneer and currently chief scientist of blockchain technology research and development firm nChain, is being sued for $10.2b by a relative of one of Bitcoin’s earliest advocates.

On Monday, word broke that Ira Kleiman, brother of deceased Bitcoin pioneer Dave Kleiman, had filed a federal lawsuit in the Southern District of Florida accusing Wright of acquiring via nefarious means some “hundreds of thousands” of Dave’s Bitcoins, along with “valuable intellectual property rights of various blockchain technologies.”

The complaint notes that Wright and Dave Kleiman shared a “longtime interest in cyber security, digital forensics, and the future of money,” and their early collaboration allowed them to accumulate “a vast wealth of bitcoins from 2009 through 2013,” the year Kleiman died following a long battle with MSRA.

The complaint says Kleiman’s family was ignorant of his Bitcoin holdings, because “for reasons not yet completely clear, [Kleiman and Wright] chose to keep their involvement in Bitcoin hidden from most of their family and friends.”